Projected changes in hydrologic niches of riparian plants in response to climate change
(English)Manuscript (preprint) (Other academic)
Riparian zones are species-rich habitats also subject to wide-spread degradation and modification. The extensive habitat and biodiversity losses make conservation of riverine ecosystems a priority, especially in the few river systems that remain free-flowing. However, riparian ecosystems might also be threatened by ongoing and anticipated climate change. Models predict large changes in flow regime across the world, which is anticipated to alter riparian communities, but how is poorly known. In northern Europe, lower annual spring flood peaks and higher winter flows are expected, resulting in narrower riparian zones. To determine the impact on riparian plant species we surveyed five sites along the free-flowing Vindel River in northern Sweden. We calculated the probability of occurrence of plant species along gradients of flood frequency and duration. We then compared present and predicted future water-level fluctuations (based on climate models and IPCC emission scenarios) and thereby got an estimate of the future extent of the species based on their hydrologic requirements. The majority of the riparian species are predicted to decrease in elevational extent by on average 13−28 % until the end of the century, depending on scenario. Species growing in the upper, spring-flood controlled part of the riparian zone are predicted to decrease most, with largest reductions in species with narrow flood duration ranges (decreases of up to 54%). Many species would become less frequent than today, with stochastic extinctions expected along some reaches. Reductions may be more dramatic along rivers in the southern boreal zone where snowmelt-fed hydrographs are expected to be largely replaced by rain-fed ones. With few rivers remaining unaffected by dams and other human stressors, even moderate reductions in abundance can have grave consequences for regional conservation, calling for monitoring to detect declining species and management actions to minimize species losses. Management might include protection of more riverine ecosystems, reduction of negative impacts from land-use activities, implementation of more environmentally friendly flows, channel restoration, and more artificial management options such as mowing riparian meadows no longer maintained by recurrent floods.
climate change, flooding, niche width, probability curves, river banks, water table, inundation duration
IdentifiersURN: urn:nbn:se:umu:diva-43809OAI: oai:DiVA.org:umu-43809DiVA: diva2:416075